The present invention relates to a method for obtaining a correction value of an optical sensor used for detecting an edge of a recording medium, as well as to a recording apparatus.
In a recording apparatus typified by a facsimile, a printer, or the like, a carriage having a recording head used for performing a recording on a recording medium is sometimes equipped with an optical sensor capable of detecting optical reflectance of a transport path (converting the intensity of reflected light into a current value) and disposed at a position opposing the transport path of the recording medium.
For instance, as described in JP-A-2004-243741, this optical sensor is used for detecting the position of an end (edge) of a recording medium in an inkjet printer. Specifically, the intensity of reflected light differs between a state where the recording medium is present and a state where the recording medium is not present. Accordingly, the position of an edge (hereinafter often called an “edge position”) of the recording medium can be acquired by means of detecting the difference. Thus, when the edge position of the recording medium can be accurately ascertained by means of the optical sensor directly detecting the edge position and when so-called frameless printing—e.g., a recording medium being printed to the edges—performed, the quantity of ink discarded in an area outside the edge of the recording medium can be minimized, the chance of generation of an ink mist can be minimized, and the volume of abandoned image data can be minimized. Accordingly, there is yielded an advantage of preventing loss of the originality of original image data.
However, if the positional relationship between the optical sensor and the recording head (an ink ejection nozzle) becomes deviated for reasons of an assembly error during assembly of an apparatus, even when the optical sensor has acquired the edge position of a recording medium, ink cannot be adhered to an appropriate position during actual recording operation by the recording head. An optical sensor has individual differences, and uniform detection accuracy of the optical sensor does not always exist among pieces of apparatus. Therefore, there arises a case where no coincidence exists between the edge position detected by the optical sensor and an actual edge position.